Image display method, image display program, and image display apparatus

ABSTRACT

An image display method by which a presence of a variation in a color signal in video, a variation in brightness data in video, a bit rate of video reproduction, an audio signal, a variation in a bit rate of video reproduction, or caption data is checked, whereby it is possible to display a significant image whose contents can be grasped by a user by skipping over a monochrome image such as a black or white image whose contents cannot be grasped by the user, even if a moving image starts from such a monochrome image.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image display method. Moreparticularly, the present invention relates to an image display methodfor displaying a digest of a moving image.

2. Description of the Background Art

When the contents of a plurality of moving images stored in a videorecording medium are checked, it is effective to display a content list(a digest screen) of thumbnail images of the moving images bysequentially reading the stored moving image data.

As one example of the video recording medium, an optical disk will bedescribed.

FIG. 13 is a flowchart for describing a conventional image displaymethod. In FIG. 13, a table stored in a predetermined location on anoptical disk is read, and addresses (minute, second, frame) of allmoving image data stored in the optical disk are obtained (S1301). Next,a start address of moving image data to be displayed is extracted(S1302), data is read from the optical disk by moving an optical head toa location of the extracted start address (S1303), and the read data isinput to an MPEG decoder (S1304). When a frame of an MPEG image isdetected in data following the start address, a size of the image dataof the frame is reduced (S1305), and a display device is caused todisplay the resultant thumbnail image (S1306). Such an operation isrepeated a predetermined times (e.g., as many as the number of imageswhich can be displayed on the display device) (S1307).

Also, there is a method of detecting audio data and displaying an Ipicture when a predetermined time period has elapsed after detection ofthe audio data (Japanese Patent Gazette No. 3110376).

In the above-described conventional image display method, a thumbnailimage of an image detected first in data following the start address isdisplayed. As a result, in the case where a moving image whose screengradually fades in (as shown in FIG. 14, for example) is included in avideo recording medium, a thumbnail image generated from such a movingimage is a black image like a thumbnail image 151 shown in FIG. 15. Assuch, the problem with the above-described conventional image displaymethod is that a user cannot grasp the contents of such a moving image.

Also, there may be a method of detecting brightness of an image fordisplaying a thumbnail image of a frame when an image whose brightnessis equal to or greater than a predetermined level is input. However, athumbnail image of a moving image which starts from a white (bright)image is plain white, and its content is impossible to understand. Assuch, a problem with the above-described method is that the user cannotgrasp the contents of such a moving image.

Also, by the method of detecting audio data and displaying an I picturewhen a predetermined time period has elapsed after detection of theaudio data, a first image may not be displayed even if the first imageof the moving image is a significant image to be displayed. Also, in thecase where a video recording medium includes a moving image on whichaudio data is not multiplexed, a digest (a thumbnail image) of such amoving image is not displayed, which is also a problem.

Therefore, an object of the present invention is to provide an imagedisplay method, an image display program, and an image display apparatuscapable of displaying a significant thumbnail image by which a user cangrasp the contents thereof when a digest of a moving image is displayed.

SUMMARY OF THE INVENTION

The present invention has the following features to solve at least oneof the above-described problems (notes in parentheses indicate exemplaryelements which can be found in the embodiments to follow, though suchnotes are not intended to limit the scope of the invention).

A first image display method of the present invention comprises a step(S205) of sequentially extracting image data of each frame from a headof moving image data; a step (S205) of generating thumbnail image datacorresponding to the extracted image data; a step (S206) determiningwhether or not the generated thumbnail image data includes more than apredetermined number of pixels having different color-difference data ina predetermined area; and a step (S208) displaying a thumbnail imagecorresponding to the thumbnail image data if it is determined that thereare more than a predetermined number of pixels having differentcolor-difference data in a predetermined area. Note that “apredetermined area” may be all pixels of the thumbnail image data, ormay be a portion of the pixels. Also, “a predetermined number” may beone, or may be two or more.

A second image display method of the present invention comprises: a step(S401) of sequentially extracting image data of each frame from a headof moving image data; a step (S402) of determining whether or not theextracted image data includes more than a predetermined number of pixelshaving different color-difference data in a predetermined area; a step(S403) of generating thumbnail image data corresponding to the imagedata if it is determined that there are more than a predetermined numberof pixels having different color-difference data in a predeterminedarea; and a step of displaying a thumbnail image corresponding to thegenerated thumbnail image data.

A third image display method of the present invention comprises: a step(S502) of sequentially extracting image data of each frame from a headof moving image data; a step (S502) of generating thumbnail image datacorresponding to the extracted image data; a step (S503) of determiningwhether or not there are more than a predetermined number of pixelswhose color-difference data is different between the generated thumbnailimage data and thumbnail image data corresponding to a preceding framein a predetermined area; and a step (S504) of displaying a thumbnailimage corresponding to the thumbnail image data if it is determined thatthere are more than a predetermined number of pixels having differentcolor-difference data in a predetermined area. Note that “a precedingframe” may be an immediately preceding frame, or may be a first frame ofthe moving image data.

A fourth image display method of the present invention comprises: a step(S602) of sequentially extracting image data of each frame from a headof moving image data; a step (S603) of determining whether or not thereare more than a predetermined number of pixels whose color-differencedata is different between the extracted image data and image datacorresponding to a preceding frame in a predetermined area; a step(S604) of generating thumbnail image data corresponding to the imagedata if it is determined that there are more than a predetermined numberof pixels having different color-difference data in a predeterminedarea; and a step (S207) of displaying a thumbnail image corresponding tothe generated thumbnail image data.

A fifth image display method of the present invention comprises: a step(S205) of sequentially extracting image data of each frame from a headof moving image data; a step (S205) of generating thumbnail image datacorresponding to the extracted image data; a step (S701) of determiningwhether or not the generated thumbnail image data includes more than apredetermined number of pixels having different brightness data in apredetermined area; and a step (S207) of displaying a thumbnail imagecorresponding to the thumbnail image data if it is determined that thereare more than a predetermined number of pixels having differentbrightness data in a predetermined area. Note that “a predeterminednumber” may be one, or may be two or more.

A sixth image display method of the present invention comprises: a stepof sequentially extracting image data of each frame from ahead of movingimage data; a step of determining whether or not the extracted imagedata includes more than a predetermined number of pixels havingdifferent brightness data in a predetermined area; a step of generatingthumbnail image data corresponding to the image data if it is determinedthat there are more than a predetermined number of pixels havingdifferent brightness data in a predetermined area; and a step ofdisplaying a thumbnail image corresponding to the generated thumbnailimage data.

A seventh image display method of the present invention comprises: astep of sequentially extracting image data of each frame from a head ofmoving image data; a step of generating thumbnail image datacorresponding to the extracted image data; a step of determining whetheror not there are more than a predetermined number of pixels whosebrightness data is different between the generated thumbnail image dataand thumbnail image data corresponding to a preceding frame in apredetermined area; and a step of displaying a thumbnail imagecorresponding to the thumbnail image data if it is determined that thereare more than a predetermined number of pixels having differentbrightness data in a predetermined area.

An eighth image display method of the present invention comprises: astep of sequentially extracting image data of each frame from a head ofmoving image data; a step of determining whether or not there are morethan a predetermined number of pixels whose brightness data is differentbetween the extracted image data and image data corresponding to apreceding frame in a predetermined area; a step of generating thumbnailimage data corresponding to the extracted image data if it is determinedthat there are more than a predetermined number of pixels havingdifferent brightness data in a predetermined area; and a step ofdisplaying a thumbnail image corresponding to the generated thumbnailimage data.

A ninth image display method of the present invention comprises: a step(S801) of sequentially extracting image data of each frame from a headof moving image data; a step (S802) of comparing a bit rate of theextracted image data and a predetermined value; a step (S803) ofgenerating thumbnail image data corresponding to the image data if it isdetermined that a bit rate of the image data exceeds a predeterminedvalue; and a step (S207) of displaying a thumbnail image correspondingto the generated thumbnail image data.

A tenth image display method of the present invention comprises: a step(S903) of sequentially extracting image data of each frame from a headof moving image data; a step (S905) of determining whether or not adifference between a bit rate of the extracted image data and a bit rateof image data of a preceding frame is equal to or greater than apredetermined value; a step (S906) of generating thumbnail image datacorresponding to the image data if the difference is equal to or greaterthan a predetermined value; and a step (S207) of displaying a thumbnailimage corresponding to the generated thumbnail image data.

An eleventh image display method of the present invention comprises: astep (S1001) of retrieving audio data included in moving image data froma head of the moving image data; a step (S205) of extracting image dataof a frame corresponding to a time period at which the audio data isdetected; a step (S205) of generating thumbnail image data correspondingto the extracted image data; and a step (S207) of displaying a thumbnailimage corresponding to the generated thumbnail image data.

A twelfth image display method of the present invention comprises: astep (S1101) of retrieving caption data included in moving image datafrom a head of the moving image data; a step (S205) of extracting imagedata of a frame corresponding to a time period at which the caption datais detected; a step (S205) of generating thumbnail image datacorresponding to the extracted image data; and a step (S207) ofdisplaying a thumbnail image corresponding to the generated thumbnailimage data.

An image display program of the present invention causes a computer (8)to execute each step of any of the first to twelfth image displaymethods.

An image display apparatus of the present invention comprises: recordingmeans (7) for recording the above-described image display program; and acomputer (8) operated based on the image display program.

Based on the present invention, when a digest of a moving image isdisplayed, it is possible to display a significant thumbnail image bywhich a user can grasp the contents thereof. As a result, the user caneasily and reliably grasp the contents of a moving image stored in avideo recording medium, for example.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a structure of an image displayapparatus according to a first embodiment of the present invention;

FIG. 2 is a flowchart showing an operation of the image displayapparatus according to the first embodiment of the present invention;

FIGS. 3A to 3C is an exemplary digest screen displayed by the imagedisplay apparatus of the present invention;

FIG. 4 is a flowchart showing an operation of an image display apparatusaccording to a second embodiment of the present invention;

FIG. 5 is a flowchart showing an operation of an image display apparatusaccording to a third embodiment of the present invention;

FIG. 6 is a flowchart showing an operation of an image display apparatusaccording to a fourth embodiment of the present invention;

FIG. 7 is a flowchart showing an operation of an image display apparatusaccording to a fifth embodiment of the present invention;

FIG. 8 is a flowchart showing an operation of an image display apparatusaccording to a sixth embodiment of the present invention;

FIG. 9 is a flowchart showing an operation of an image display apparatusaccording to a seventh embodiment of the present invention;

FIG. 10 is a flowchart showing an operation of an image displayapparatus according to an eighth embodiment of the present invention;

FIG. 11 is a flowchart showing an operation of an image displayapparatus according to a ninth embodiment of the present invention;

FIG. 12 is a flowchart showing an operation of an image displayapparatus according to a tenth embodiment of the present invention;

FIG. 13 is a flowchart showing an operation of a conventional imagedisplay apparatus;

FIG. 14 is an example of moving image data; and

FIG. 15 is an exemplary digest screen displayed by the conventionalimage display apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

With reference to the drawings, embodiments of the present inventionwill be described in detail by taking an optical disk for example.

FIG. 1 is a block diagram showing a structure of an image displayapparatus according to a first embodiment of the present invention. FIG.2 is a flowchart showing an operation of this image display apparatus.The image display apparatus includes an optical disk drive 2 for readingdata from an optical disk 1, an MPEG decoder 3 for decoding MPEG encodedaudio data and moving image data, an image memory 4 for storing imagedata decoded by the MPEG decoder 3, a display controller 6 for causing adisplay device 5 to display image data stored in the image memory 4, aROM 7 for storing an image display program, a CPU 8 for controlling theapparatus in accordance with the program, a RAM 9 for storing anaddress, etc., of moving image data, and an input device 10 used by auser for giving an instruction.

With reference to FIG. 2, an operation of the above-described imagedisplay apparatus will be described. First, when the optical disk 1 ismounted on the optical disk drive 2, the CPU 8 causes the optical diskdrive 2 to read a table stored in a predetermined location on theoptical disk 1. In this table, addresses (minute, second, frame) of allMPEG encoded moving image data stored in the optical disk 1 areregistered. Then, the CPU 8 stores the obtained addresses of the movingimage data in the RAM 9 (S201).

The CPU 8 retrieves a start address of the moving image data to bedisplayed from the RAM 9 (S202), reads data from the optical disk 1 bymoving an optical head of the optical disk drive 2 to a location of thestart address of the moving image data to be displayed on the opticaldisk 1 (S203), and inputs the read data to the MPEG decoder 3 (S204).

The MPEG decoder 3 decodes the MPEG encoded data. When an output of aframe following the start address of the moving image data to bedisplayed is detected, the CPU 8 reduces a size of the image dataobtained as a result of decoding by the MPEG decoder 3 (S205), andwrites the thumbnail image data generated as a result of a sizereduction process to a predetermined memory area in the image memory 4.Further, the CPU 8 compares among color-difference components(color-difference data) of the pixels of the thumbnail image datawritten to the image memory 4 for determining whether or not there is avariation in the color-difference data (that is, whether or not thethumbnail image data includes pixels having different color-differencedata) (S206). If there is no variation in the color-difference data, theCPU goes back to step S205, and performs the same process for a nextframe. After repeating the processes at steps S205 and S206, ifdetermination is finally made at step S206 that the thumbnail image datawritten to the image memory 4 includes pixels having differentcolor-difference data, the CPU 8 instructs the display controller 6 todisplay a thumbnail image based on the above thumbnail image data on thedisplay device 5 (step S207). As a result, as shown in FIG. 3A, athumbnail image 31 is displayed on the display device 5.

The CPU 8 subsequently determines whether or not another thumbnail imageis further displayed by checking, for example, whether or not there ismoving image data whose thumbnail image has yet to be displayed in theoptical disk 1 (S208). If it is determined that another thumbnail imageis to be displayed, the CPU 8 goes back to step S202, and repeats thesame process for moving image data to be displayed next. The thumbnailimage data obtained by the above process is written to a memory area,which is different from the area to which the thumbnail image 31 waswritten, in the image memory 4. As a result, as shown in FIG. 3B, a newthumbnail image 32 is displayed next to the thumbnail image 31. Byrepeating the above-described operation, a digest screen as shown inFIG. 3C in which a plurality of thumbnail images are arranged isdisplayed.

Note that, in FIG. 3C, seven thumbnail images are displayed on thescreen, but the present invention is not limited thereto. It will beunderstood that the number of thumbnail images displayed on the screenmay be arbitrary. Also, in the case where the number of thumbnail imagesgenerated from the moving image data stored in the optical disk 1exceeds the maximum number of thumbnail images that can be displayed onone screen (for example, in FIG. 3C, the maximum number is nine), theCPU 8 may newly start displaying after deleting all displayed thumbnailimages. Alternatively, the CPU 8 may leave a portion of the displayedthumbnail images, and arrange newly generated thumbnail images nextthereto.

Note that, at step S206, determination about whether or not there is adifference in the color-difference component may be made inconsideration of all pixels of the thumbnail image. Alternatively, thedetermination may be made in consideration of a portion of pixels (e.g.,pixels near the center of the thumbnail image) of the thumbnail image.If determination is made in consideration of a portion of the pixels, itis possible to reduce the processing load at step S206.

Note that, in the present embodiment, a thumbnail image is displayed ifthe thumbnail image includes pixels having different color-differencedata. However, the present invention is not limited thereto. Forexample, a thumbnail image may be displayed only in the case where thethumbnail image includes three or more pixels having differentcolor-difference data (that is, in the case where the thumbnail imageincludes three or more colors). Similarly, a thumbnail image may bedisplayed only in the case where the thumbnail image includes four ormore pixels having different color-difference data. Thus, it is possibleto display a further significant thumbnail image.

As such, in the present embodiment, thumbnail images are sequentiallygenerated from a head of the moving image, and a thumbnail image havingdifferent color-difference components is displayed as a digest, wherebyit is possible to prevent a black or white image from being displayed asa digest. As a result, it is possible to display a significant digestscreen allowing the user to easily grasp the contents of the movingimage stored in the optical disk 1.

Second Embodiment

FIG. 4 is a flowchart showing an operation of an image display apparatusaccording to a second embodiment of the present invention. In FIG. 4,any steps identical to their counterparts in FIG. 2 are denoted by likestep numbers, with the descriptions thereof omitted. The structure ofthe image display apparatus of the second embodiment is identical to itscounterpart in the first embodiment (in this embodiment, however, theCPU 8 executes a different image processing program), and therefore FIG.1 is used in the following descriptions.

In the first embodiment, comparison of a color difference is performedby referring to thumbnail image data. The present embodiment ischaracterized in that comparison of a color difference is performed byreferring to image data for which a size reduction process has not beenperformed.

When an output of a frame following a start address of moving image datato be displayed is detected (S401), the CPU 8 compares acolor-difference component of each pixel of the image data of this framefor determining whether or not there is a variation in color-differencedata in this image (S402). If there is no variation in thecolor-difference data, the CPU 8 goes back to step S401, and performsthe same process for a next frame. After repeating the processes atsteps S401 and S402, if determination is finally made at step S402 thata piece of image data includes pixels having different color-differencedata, the CPU 8 reduces a size of the image data (S403), and writes thethumbnail image generated as a result of a size reduction process to apredetermined memory area in the image memory 4. Then, at step S207, athumbnail image is displayed based on the above-described thumbnailimage data.

Note that, at step S402, determination about whether or not there is adifference in the color-difference component may be made inconsideration of all pixels of the image. Alternatively, thedetermination may be made in consideration of a portion of pixels (e.g.,pixels near the center of the thumbnail image) of the image. Ifdetermination is made in consideration of a portion of the pixels, it ispossible to reduce the processing load at step S402.

In the present embodiment, it is assumed that a thumbnail imagecorresponding to an image including pixels having differentcolor-difference data is displayed. However, the present invention isnot limited thereto. For example, only in the case where an imageincludes three or more pixels having different color-difference data(that is, in the case where the image includes three or more colors), athumbnail image corresponding to the image may be displayed. Similarly,only in the case where an image includes four or more pixels havingdifferent color-difference data, a thumbnail image corresponding to theimage may be displayed. Thus, it is possible to display a furthersignificant thumbnail image.

As such, in the present embodiment, an image having differentcolor-difference components is retrieved from a head of the movingimage, and a thumbnail image corresponding to the image is displayed asa digest, whereby it is possible to prevent a black or white image frombeing displayed as a digest. As a result, it is possible to display adigest screen allowing the user to easily grasp the contents of themoving image stored in the optical disk 1.

Note that, compared to the second embodiment, the above-mentioned firstembodiment has the following advantages: comparison of a colordifference of each pixel requires a smaller processing load since thesignificance of an image is determined based on a thumbnail image whosesize is smaller than an original image; and more precise determinationresults can be obtained since the significance of an image is determinedbased on a thumbnail image actually displayed on the screen.

Third Embodiment

FIG. 5 is a flowchart showing an operation of an image display apparatusaccording to a third embodiment of the present invention. In FIG. 5, anysteps identical to their counterparts in FIG. 2 are denoted by like stepnumbers, with the descriptions thereof omitted. The structure of theimage display apparatus of the third embodiment is identical to itscounterpart in the first embodiment (in this embodiment, however, theCPU 8 executes a different image processing program), and therefore FIG.1 is used in the following descriptions.

In the first embodiment, a color difference is compared among pixels ofthe same thumbnail image data. The present embodiment is characterizedin that a color difference is compared between two pieces of thumbnailimage data on a pixel basis.

When an output of a frame following a start address of moving image datato be displayed is detected, the CPU 8 reduces a size of the image dataobtained as a result of decoding by the MPEG decoder 3 (S501), andwrites the thumbnail image data (that is, thumbnail image datacorresponding to a first frame; hereinafter, referred to as firstthumbnail image data) generated as a result of a size reduction processto a predetermined memory area in the image memory 4. Further, the CPU 8detects an output of a next frame, performs a size reduction process forimage data of this frame, and writes the thumbnail image data(hereinafter, referred to as second thumbnail image data) generated as aresult of a size reduction process to a predetermined memory area in theimage memory 4 (S502). Subsequently, the CPU 8 compares acolor-difference component (color-difference data) between the firstthumbnail image data and the second thumbnail image data on a pixelbasis for determining whether or not there is a difference in thecolor-difference data (that is, there is a pixel whose color-differencedata is different between the first thumbnail image data and the secondthumbnail image data) (S503). If there is no difference in thecolor-difference data, the CPU 8 goes back to step S502, and performsthe same process using thumbnail image data of a next frame as secondthumbnail image data. After repeating the processes at steps S502 andS503, if determination is finally made at step S503 that there is apixel whose color-difference data is different between the firstthumbnail image data and the second thumbnail image data, the CPU 8instructs the display controller 6 to display a thumbnail image based onthe second thumbnail image data on the display device 5 (S504).

Note that, at step S503, determination about whether or not there is adifference in the color-difference component may be made inconsideration of all pixels of each thumbnail image data. Alternatively,the determination may be made in consideration of a portion of pixels(e.g., pixels near the center of the thumbnail image) of each thumbnailimage data. If determination is made in consideration of a portion ofthe pixels, it is possible to reduce the processing load at step S503.

Also, in the present embodiment, a thumbnail image of a first frame isused as first thumbnail image data. However, the present invention isnot limited thereto. For example, a thumbnail image of a frameimmediately before the second thumbnail image data may be sequentiallyused as first thumbnail image data for comparing a color-differencecomponent between the frame and a next frame.

As such, in the present embodiment, first thumbnail image data whosecolor-difference component is different from thumbnail image data ofahead of the moving image is retrieved, and a thumbnail imagecorresponding to the thumbnail image data is displayed as a digest,whereby it is possible to prevent a black or white image from beingdisplayed as a digest. As a result, it is possible to display asignificant digest screen allowing the user to easily grasp the contentsof the moving image stored in the optical disk 1.

Fourth Embodiment

FIG. 6 is a flowchart showing an operation of an image display apparatusaccording to a fourth embodiment of the present invention. In FIG. 6,any steps identical to their counterparts in FIG. 2 are denoted by likestep numbers, with the descriptions thereof omitted. The structure ofthe image display apparatus of the fourth embodiment is identical to itscounterpart in the first embodiment (in this embodiment, however, theCPU 8 executes a different image processing program), and therefore FIG.1 is used in the following descriptions.

In the third embodiment, comparison of a color difference is performedby referring to two pieces of thumbnail image data. The presentembodiment is characterized in that comparison of a color difference isperformed by referring to two pieces of image data for which a sizereduction process has not been performed.

When an output of a frame following a start address of the moving imagedata to be displayed is detected, the CPU 8 writes the image data (thatis, image data corresponding to a first frame; hereinafter, referred toas first image data) obtained as a result of decoding by the MPEGdecoder 3 to a predetermined memory area in the image memory 4 (S601).Further, the CPU 8 detects an output of a next frame, and writes thisimage data (hereinafter, referred to as second image data) to apredetermined memory area in the image memory 4 (S602). Subsequently,the CPU 8 compares a color-difference component (color-difference data)between the first image data and the second image data, which arewritten to the image memory 4, on a pixel basis for determining whetheror not there is a difference in the color-difference data (that is,there is a pixel whose color-difference data is different between thefirst image data and the second image data (S603). If there is nodifference in the color-difference data, the CPU 8 goes back to stepS602, and performs the same process using image data of a next frame assecond image data. After repeating the processes at steps S602 and S603,if determination is finally made at step S603 that there is a pixelwhose color-difference data is different between the first image dataand the second image data, the CPU 8 reduces a size of the second imagedata (S604), and writes the thumbnail image data generated as a resultof a size reduction process to a predetermined memory area in the imagememory 4. Then, at step S207, a thumbnail image is displayed based onthe above-described thumbnail image data.

Note that, at step S603, determination about whether or not there is adifference in the color-difference component may be made inconsideration of all pixels of each image data. Alternatively, thedetermination may be made in consideration of a portion of pixels (e.g.,pixels near the center of the image) of each image data. Ifdetermination is made in consideration of a portion of the pixels, it ispossible to reduce the processing load at step S603.

Also, in the present embodiment, an image of a first frame is used asfirst image data. However, the present invention is not limited thereto.For example, a thumbnail image of a frame immediately before the secondimage data may be sequentially used as first image data for comparing acolor-difference component between the frame and a next frame.

As such, in the present embodiment, first image data whosecolor-difference component is different from image data of a head of themoving image is retrieved, and a thumbnail image corresponding to theimage data is displayed as a digest, whereby it is possible to prevent ablack or white image from being displayed as a digest. As a result, itis possible to display a significant digest screen allowing the user toeasily grasp the contents of the moving image stored in the optical disk1.

Note that, compared to the fourth embodiment, the above-mentioned thirdembodiment has the following advantages: comparison of a colordifference of each pixel requires a smaller processing load since thesignificance of an image is determined based on a thumbnail image whosesize is smaller than an original image; and more precise determinationresults can be obtained since the significance of an image is determinedbased on a thumbnail image actually displayed on the screen.

Fifth Embodiment

In the above-described first to fourth embodiments, determination aboutwhether or not an image is significant is made based on a colordifference. In place of color difference data, it is also effective todetermine whether or not an image is significant based on brightness. Inthis case, “a color difference” in the first to fourth embodiments maybe replaced with “brightness” for describing an operation of the imageprocessing apparatus. By way of example, “a color difference” in thefirst embodiment is replaced with “brightness” for describing the firstembodiment as a fifth embodiment.

FIG. 7 is a flowchart showing an operation of an image display apparatusaccording to the fifth embodiment of the present invention. In FIG. 7,any steps identical to their counterparts in FIG. 2 are denoted by likestep numbers, with the descriptions thereof omitted. The structure ofthe image display apparatus of the fifth embodiment is identical to itscounterpart in the first embodiment (in this embodiment, however, theCPU 8 executes a different image processing program), and therefore FIG.1 is used in the following descriptions.

The CPU 8 compares among brightness components (brightness data) of thepixels of the thumbnail image data written to the image memory 4 fordetermining whether or not there is a variation in the brightness data(that is, whether or not the thumbnail image data includes pixels havingdifferent brightness data) (S701). If there is no variation in thebrightness data, the CPU goes back to step S205, and performs the sameprocess for a next frame. After repeating the processes at steps S205and S701, if determination is finally made at step S701 that thethumbnail image data written to the image memory 4 includes pixelshaving different brightness data, the CPU 8 instructs the displaycontroller 6 to display a thumbnail image based on the above thumbnailimage data on the display device 5 (step S207).

Note that, at step S701, determination about whether or not there is adifference in the brightness component may be made in consideration ofall pixels of the thumbnail image. Alternatively, the determination maybe made in consideration of a portion of pixels (e.g., pixels near thecenter of the thumbnail image) of the thumbnail image. If determinationis made in consideration of a portion of the pixels, it is possible toreduce the processing load at step S701.

Note that, in the present embodiment, a thumbnail image is displayed ifthe thumbnail image includes pixels having different brightness data.However, the present invention is not limited thereto. For example, athumbnail image may be displayed only in the case where the thumbnailimage includes three or more pixels having different brightness data.Similarly, a thumbnail image may be displayed only in the case where thethumbnail image includes four or more pixels having different brightnessdata. Thus, it is possible to display a further significant thumbnailimage.

As such, in the present embodiment, a thumbnail image is sequentiallygenerated from a head of the moving image, and a thumbnail image havingdifferent brightness components is displayed as a digest, whereby it ispossible to prevent a black or white image from being displayed as adigest. As a result, it is possible to display a significant digestscreen allowing the user to easily grasp the contents of the movingimage stored in the optical disk 1.

Note that “a color difference” in the second to fourth embodiments canbe replaced with “brightness” in similar manners. In this case, astructure and an operation of the image processing apparatus would beobvious over the descriptions of each embodiment.

Sixth Embodiment

FIG. 8 is a flowchart showing an operation of an image display apparatusaccording to a sixth embodiment of the present invention. In FIG. 8, anysteps identical to their counterparts in FIG. 2 are denoted by like stepnumbers, with the descriptions thereof omitted. The structure of theimage display apparatus of the sixth embodiment is identical to itscounterpart in the first embodiment (in this embodiment, however, theCPU 8 executes a different image processing program), and therefore FIG.1 is used in the following descriptions.

When an output of a frame following a start address of the moving imagedata to be displayed is detected (S801), the CPU 8 calculates a bit rateof the image data obtained as a result of decoding by the MPEG decoder3, and determines whether or not the calculated bit rate is equal to orgreater than a predetermined value (S802). If the calculated bit rate issmaller than a predetermined value (that is, the image is a monotonousimage), the CPU 8 goes back to step S801 for checking an output of anext frame and calculating a bit rate of the next frame. The CPU 8repeats the above-described process. When image data whose bit rate isequal to or greater than a predetermined value is detected, the CUP 8reduces a size of the image data, and writes the thumbnail image data toa predetermined memory area in the image memory 4 (S803). Then, at stepS207, a thumbnail image is displayed based on the above-describedthumbnail image data.

As such, in the present embodiment, a frame whose bit rate is equal toor greater than a predetermined value is retrieved from ahead of themoving image, and the retrieved frame is displayed as a digest, wherebyit is possible to prevent a black or white image from being displayed asa digest. As a result, it is possible to display a significant digestscreen allowing the user to easily grasp the contents of the movingimage stored in the optical disk 1.

Seventh Embodiment

FIG. 9 is a flowchart showing an operation of an image display apparatusaccording to a seventh embodiment of the present invention. In FIG. 9,any steps identical to their counterparts in FIG. 2 are denoted by likestep numbers, with the descriptions thereof omitted. The structure ofthe image display apparatus of the seventh embodiment is identical toits counterpart in the first embodiment (in this embodiment, however,the CPU 8 executes a different image processing program), and thereforeFIG. 1 is used in the following descriptions.

When an output of a frame following a start address of the moving imagedata to be displayed is detected (S901), the CPU 8 calculates a bit rateof the image data (which corresponds to a first frame) obtained as aresult of decoding by the MPEG decoder 3, and stores the calculated bitrate (S902). Assume that the above-described bit rate is (A). Further,the CPU 8 detects an output of a next frame (S903), calculates a bitrate of image data (hereinafter, referred to as second image data) ofthis frame, and stores the calculated bit rate (S904). Assume that theabove-described bit rate is (B). Then, the CPU 8 determines whether ornot the bit rate (A) is equal to the bit rate (B) (S905). If the bitrate (A) is equal to the bit rate (B), the CPU 8 goes back to step S903,and performs the same process using a bit rate of a next frame as a bitrate (B). After repeating the processes from steps S903 to S905, if aframe having a different bit rate is finally detected, the CPU 8 reducesa size of image data of the frame (S906). Then, at step S207, athumbnail image is displayed based on the above-described thumbnailimage data.

Note that, in the present embodiment, the CPU 8 determines at step S905whether or not a bit rate (A) is equal to a bit-rate (B), but thepresent invention is not limited thereto. For example, the CPU 8 maydetermine whether or not a difference between the bit rate (A) and thebit rate (B) is equal to or greater than a predetermined value.

Also, in the present embodiment, a bit rate of a first frame is used asa bit rate (A), but the present invention is not limit thereto. Forexample, a bit rate of a frame immediately before the second image datamay be used as a bit rate (A) for performing comparison of a bit ratebetween the frame and a next frame.

As such, in the present embodiment, a frame having a changed bit rate isretrieved from a head of the moving image, and the retrieved frame isdisplayed as a digest, whereby it is possible to prevent a black orwhite image from being displayed as a digest. As a result, it ispossible to display a significant digest screen allowing the user toeasily grasp the contents of the moving image stored in the optical disk1.

Eighth Embodiment

FIG. 10 is a flowchart showing an operation of an image displayapparatus according to an eighth embodiment of the present invention. InFIG. 10, any steps identical to their counterparts in FIG. 2 are denotedby like step numbers, with the descriptions thereof omitted. Thestructure of the image display apparatus of the eighth embodiment isidentical to its counterpart in the first embodiment (in thisembodiment, however, the CPU 8 executes a different image processingprogram), and therefore FIG. 1 is used in the following descriptions.

When an MPEG encoded audio data is detected in data following a startaddress (S1001), the CPU 8 detects an output of a frame after a timeperiod represented by an address of the detected audio data, reduces asize of the frame (S205), and writes the thumbnail image data to apredetermined memory area in the image memory 4. Then, at step S207, athumbnail image is displayed based on the above-described thumbnailimage data.

As such, in the present embodiment, a frame after a time period at whichaudio data is first detected is retrieved from a head of a moving image,and the retrieved frame is displayed as a digest, whereby it is possibleto prevent a screen corresponding to a silent frame from being displayedas a digest. As a result, it is possible to display a significant digestscreen allowing the user to easily grasp the contents of the movingimage stored in the optical disk 1.

Ninth Embodiment

FIG. 11 is a flowchart showing an operation of an image displayapparatus according to a ninth embodiment of the present invention. InFIG. 11, any steps identical to their counterparts in FIG. 2 are denotedby like step numbers, with the descriptions thereof omitted. Thestructure of the image display apparatus of the ninth embodiment isidentical to its counterpart in the first embodiment (in thisembodiment, however, the CPU 8 executes a different image processingprogram), and therefore FIG. 1 is used in the following descriptions.

When MPEG encoded caption data is detected in data following a startaddress (S1101), the CPU 8 detects a frame after a time periodrepresented by an address of the detected caption data, reduces a sizeof the frame (S205), and writes the thumbnail image data to apredetermined memory area in the image memory 4. Then, at step S207, athumbnail image is displayed based on the above-described thumbnailimage data.

As such, in the present embodiment, a frame after a time period at whichcaption data is detected is retrieved from a head of a moving image, andthe retrieved frame is displayed as a digest, whereby it is possible toprevent a screen corresponding to a frame without speech in the movingimage with the captions from being displayed as a digest. As a result,it is possible to display a significant digest screen allowing the userto easily grasp the contents of the moving image stored in the opticaldisk 1.

Tenth Embodiment

FIG. 12 is a flowchart showing an operation of an image displayapparatus according to a tenth embodiment of the present invention. InFIG. 12, any steps identical to their counterparts in FIG. 2 are denotedby like step numbers, with the descriptions thereof omitted. Thestructure of the image display apparatus of the tenth embodiment isidentical to its counterpart in the first embodiment (in thisembodiment, however, the CPU 8 executes a different image processingprogram), and therefore FIG. 1 is used in the following descriptions.

The present embodiment corresponds to a combination of theabove-described first embodiment and the eighth embodiment.

When an MPEG encoded audio data is detected in data following a startaddress (S1001), the CPU 8 detects an output of a frame after a timeperiod represented by an address of the detected audio data, reduces asize of the frame (S205), and writes the thumbnail image data to apredetermined memory area in the image memory 4. Subsequently, the CPU 8compares among color-difference components of the pixels of thethumbnail image written to the image memory 4 for checking whether ornot there is a variation in the color-difference data (S206). If thereis no variation in the color-difference data, the CPU 8 goes back tostep S205. After repeating the processes at steps S205 and S206, the CPU8 instructs the display controller 6 to display a thumbnail imageincluding pixels having different color-difference data (step S207).

As such, in the present embodiment, a plurality of methods for detectinga significant thumbnail image are combined, whereby it is possible todisplay a further significant thumbnail image. Also, a process forgenerating a thumbnail image can be omitted until detection of audiodata, whereby it is possible to reduce time required for retrieving asignificant thumbnail image.

Note that the tenth embodiment is a combination of the first embodimentand the eighth embodiment, but a combination is not limited thereto. Forexample, three or more embodiments may be combined.

Note that, in the above-described first to tenth embodiments, a digestof MPEG encoded moving image data stored in the optical disk 1 isdisplayed, but the present invention is not limited thereto. Forexample, the present invention can be applied to a case in which adigest of moving image data stored in a recording medium other than theoptical disk 1 (e.g., a hard disk) is displayed. Also, the presentinvention can be applied to a case in which a digest of moving imagedata other than MPEG encoded moving image data is displayed.

Also, in the above-described first to tenth embodiments, an imageprocessing program is stored in the ROM 7. The image processing programmay be stored in an arbitrary computer readable recording medium such asa CD-ROM or a hard disk, or may be supplied to the image processingapparatus via a communication line.

Note that, in the first to tenth embodiments, a significant image isdetected from a start address of each moving image. However, the presentinvention is not limited thereto. An address may be detected from astart address in reverse. As a result, in the case where the movingimage is reproduced from the detected image, it is possible to reproducedesired data without skipping a start address thereof.

While the invention has been described in detail, the foregoingdescription is in all aspects illustrative and not restrictive. It isunderstood that numerous other modifications and variations can bedevised without departing from the scope of the invention.

1-14. (canceled)
 15. An image display method for displaying a digest ofa moving image, comprising the steps of: sequentially extracting imagedata of each frame of moving image data; determining whether or notthere are more than a predetermined number of pixels whosecolor-difference data is different between the extracted image data andimage data corresponding to a preceding frame; generating thumbnailimage data corresponding to the extracted image data if it is determinedthat there are more than a predetermined number of pixels havingdifferent color-difference data; and displaying a thumbnail imagecorresponding to the generated thumbnail image data.
 16. An imagedisplay method for displaying a digest of a moving image, comprising thesteps of: sequentially extracting image data of each frame from a headof moving image data; determining whether or not there are more than apredetermined number of pixels whose color-difference data is differentbetween the extracted image data and image data corresponding to apreceding frame in a predetermined area; generating thumbnail image datacorresponding to the extracted image data if it is determined that thereare more than a predetermined number of pixels having differentcolor-difference data in a predetermined area; and displaying athumbnail image corresponding to the generated thumbnail image data. 17.The image display method according to claim 15, wherein the step ofdetermining whether or not there are more than the predetermined numberof pixels whose color-difference data is different between the extractedimage data and image data corresponding to the preceding frame on apixel-by-pixel.
 18. The image display method according to claim 16,wherein the step of determining whether or not there are more than thepredetermined number of pixels whose color-difference data is differentbetween the extracted image data and image data corresponding to thepreceding frame on a pixel-by-pixel.